Field
This disclosure is related to the field of video coding and compression. In particular, it is related to scalable video coding (SVC), including SVC for High Efficiency Video Coding (HEVC), Scalable HEVC (SHVC), and HEVC-based SHVC (HEVC-SHVC).
Description of the Related Art
Digital video capabilities can be incorporated into a wide range of devices, including digital televisions, digital direct broadcast systems, wireless broadcast systems, personal digital assistants (PDAs), laptop or desktop computers, tablet computers, e-book readers, digital cameras, digital recording devices, digital media players, video gaming devices, video game consoles, cellular or satellite radio telephones, so-called “smart phones,” video teleconferencing devices, video streaming devices, and the like. Digital video devices implement video coding techniques, such as those described in the standards defined by MPEG-2, MPEG-4, ITU-T H.263, ITU-T H.264/MPEG-4, Part 10, Advanced Video Coding (AVC), the High Efficiency Video Coding (HEVC) standard presently under development, and extensions of such standards. The video devices may transmit, receive, encode, decode, and/or store digital video information more efficiently by implementing such video coding techniques.
Video coding techniques include spatial (intra-picture) prediction and/or temporal (inter-picture) prediction to reduce or remove redundancy inherent in video sequences. For block-based video coding, a video slice (e.g., a video frame or a portion of a video frame) may be partitioned into video blocks, which may also be referred to as treeblocks, coding units (CUs) and/or coding nodes. Video blocks in an intra-coded (I) slice of a picture are encoded using spatial prediction with respect to reference samples in neighboring blocks in the same picture. Video blocks in an inter-coded (P or B) slice of a picture may use spatial prediction with respect to reference samples in neighboring blocks in the same picture or temporal prediction with respect to reference samples in other reference pictures. Pictures may be referred to as frames, and reference pictures may be referred to a reference frames.
Spatial or temporal prediction results in a predictive block for a block to be coded. Residual data represents pixel differences between the original block to be coded and the predictive block. An inter-coded block is encoded according to a motion vector that points to a block of reference samples forming the predictive block, and the residual data indicating the difference between the coded block and the predictive block. An intra-coded block is encoded according to an intra-coding mode and the residual data. For further compression, the residual data may be transformed from the pixel domain to a transform domain, resulting in residual transform coefficients, which then may be quantized. The quantized transform coefficients, initially arranged in a two-dimensional array, may be scanned in order to produce a one-dimensional vector of transform coefficients, and entropy coding may be applied to achieve even more compression.
High level syntax-only scalable video coding enables video blocks in a current layer to be predicted using video blocks from a reference layer without introducing low-level changes to the HEVC coding specification. For example, HLS-only SVC enables such coding by using existing inter coding techniques with reference layers from the same access unit of the current layer. Current techniques enable multiple reference layers to be identified for possible use in inter-layer coding. However, it would be advantageous to be able to restrict inter-layer coding such that, at most, only one reference layer is able to be identified as an inter-layer reference layer. Selectivly restricting inter-layer coding (e.g., inter-layer prediction) such that only one reference layer is able to be used as an inter-layer reference layer can improve coding performance, and reduce implementation complexity as well as implementation cost.